Resident Physician Vanderbilt University Medical Center Nashville, Tennessee
Objective: To investigate whether revision surgery with the same device results in a change in three key indicators of electrode positioning: scalar location, mean perimodiolar distance (𝑀𝑀 ), and angular insertion depth (AID).
Study Design: Retrospective analysis of a cochlear implant database from 2017 to 2021.
Setting: University-based tertiary medical center.
Patients: Sixteen patients underwent revision cochlear implantation with same device.
Interventions: Intra-operative CT scans were obtained after initial and revision implantation. Electrode position was calculated using auto-segmentation techniques.
Main Outcome Measures: Initial and revision scalar location, 𝑀𝑀 , and AID were compared. Changes in electrode positioning were calculated for all combinations of initial and revision electrodes.
Results: Mean change in 𝑀𝑀 for all ears was -0.07 (95% CI [-0.18, 0.03]) (P = 0.16). The mean change in AID for all ears was -5⁰ (95% CI [-35⁰, 25⁰]) (P = 0.72). Overall, there was no significant difference in 𝑀𝑀 or AID for any of the initial and revision electrode combinations studied. Three initial implantations with pre-curved electrodes resulted in a translocation from Scala Tympani (ST) to Scala Vestibuli (SV). Two remained translocated after revision, while one was corrected when revised with a straight electrode. An additional 5 translocations occurred only after revision.
Conclusions: In this study examining revision cochlear implantation with a single device, we demonstrated no significant change in key indicators of cochlear positioning, even when revising with a different style of electrode. However, the revision electrode is not necessarily confined by the initial trajectory and additional translocations can occur.
*Professional Practice Gap & Educational Need: With increasing prevalence and longer duration of device use, rates of revision cochlear implantation can only be expected to continue to rise. In this study we sought to understand the effect of revision surgery on electrode positioning.
*Learning Objective: We demonstrate that there is no significant difference in key indicators of electrode positioning after revision cochlear implantation, even when revising with a different type of electrode. There may be an increased risk of translocation during revision cochlear implantation, although this requires further study.
*Desired Result: To demonstrate that overall revision cochlear implantation does not result in significant change in electrode positioning but that the revision electrode is not necessarily confined to the tract of the initially implanted electrode.
*Level of Evidence: LEVEL V – Case series, studies with no controls
*Indicate IRB or IACUC: Vanderbilt University Medical Center, IRB #101743, #090155, #202094